This standard applies to the determination of grain acidity. GB/T 5517-1985 Grain and oil inspection Grain acidity determination method GB/T5517-1985 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Inspection of grain and oilseedsMethods for determination of acidity of grain
Inspection of grain and oilseedsMethods for determination of acidity of grainThis standard applies to the determination of the acidity of commercial grain. Apparatus and equipment
1.1 Conical flask: 100, 250ml;
1.2 Measuring cylinder: 250ml;
1.3 Funnel and funnel stand;
1.4 Balance: sensitivity 0.01g;
1.5 Pipette: 10, 20ml;
1.6 Burette, etc.
2 Reagents
2.1 0.01N potassium hydroxide or sodium hydroxide solution: 2.2 Toluene;
2.3 Chloroform;
2.4 1.0% phenol ethanol solution;
2.5 Distilled water without carbon dioxide (heat the water to boil for 15 minutes to expel carbon dioxide) 2.6 Filter paper, etc.
3 Operation method
GB/T5517-85
Weigh 15g of powder sample (grind the powder to pass through a 40-mesh sieve and measure immediately after grinding), pour it into a 250ml conical flask, add 150ml of water (use a small amount of water to mix the sample into a thin paste, then add all the water), drip 5 drops of toluene and chloroform, shake well and add a stopper, place at room temperature for 2h, shake once every 15min, filter with dry filter paper, take 10ml of filtrate with a pipette, inject
into a 100ml conical flask, add 20ml of distilled water and 3 drops of phenolic indicator, titrate with 0.01N alkali solution until the slightly red color does not disappear within 0.5min
, and record the milliliters of alkali solution consumed. Use 30ml of distilled water for a blank test and record the milliliters of alkali solution consumed. Calculation of results
Acidity is calculated according to the following formula:
Acidity (lye ml/10g grain) = (V1-V2)×Where: V1—
Volume of lye consumed by the sample filtrate, ml;
Volume of lye consumed by the blank test, ml; V2-
V3——Volume of water added for soaking the sample, ml;bzxz.net
V4—Volume of filtrate used for titration, ml;
N—Alkaline solution equivalent concentration, N;
W—Sample weight, g.
The allowable difference between the two test results shall not exceed 0.5 (lye ml/10g grain), and the average shall be the test result. The test result shall be rounded to the first decimal place.
Additional notes:
This standard is proposed by the Ministry of Commerce of the People's Republic of China. This standard is drafted by the Grain Storage and Transportation Bureau of the Ministry of Commerce. The main drafters of this standard are Gao Xiuwu, Yang Haoran, Wu Yanxia and Lv Guifen. Issued by the National Bureau of Standards on November 2, 1985
Implemented on July 1, 1986
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